Circuit Testing, General | Stanley Black & Decker HP TWIN8 instruction

CIRCUIT TESTING

GENERAL

Tests and adjustments should be performed periodically to ensure the power unit is operating at maximum efficiency. Use a calibrated flow and pressure tester. This tester can be used to isolate problems in both the engine and hydraulic system prior to any power unit disassembly.

TESTING THE HYDRAULIC CIRCUIT

The following tests can be performed to ensure that the hydraulic pump is supplying the correct flow and pressure and that the system relief valve is operating properly.

During these tests, make sure the engine is warm and operating smoothly. If test results are not as specified, refer to the troubleshooting table in this section for possible causes.

TESTING THE 5 OR 8 GPM CIRCUIT

To test the circuit, proceed as follows:

Throttle Control Lever

Flow Control Lever(s)

1.Install a calibrated flow and pressure tester across the two hose ends (where the tool would normally be connected).

2.Set both flow control levers to the OFF (down) position.

3.Set the throttle control lever to the far left for 5 GPM, after the engine is started you can leave the lever in this position if you are testing the 5 GPM circuit or move the lever to the far right to test the 8

GPM circuit.

4.Check that the tester restrictor valve is fully open (counterclockwise) on the flow and pressure tester.

5.Start the engine and allow it to run until warm.

6.With the throttle control in the far left position, the (5-GPM) circuit can be tested, or moving the lever to the far right will allow testing the (8-GPM) circuit.

a.5-GPM Range 4-6 gpm/15-23 lpm

b.8-GPM Range 7-9 gpm/26.5-34 lpm

7.Slowly turn the restrictor valve clockwise while watching the pressure gauge. The flow rate shown above in step 6 should stay at the selected flow range.

8.When the pressure reaches 2100–2200 psi/145– 152 bar, the relief valve should begin to open. The pressure at which the relief valve just begins to open is commonly referred to as the “cracking pressure”. At the “cracking pressure,” the flow rate should start to drop because the relief valve is allowing fluid to bypass to the hydraulic reservoir. The “cracking pressure” is preset at the factory and if it is not within the above range (2100-2200) psi, the relief valve must be re-set as follows: The relief valves are located on the control block which is directly behind the couplers on the dash panel

(See item 10, pg-22) for location. Use a wrench to loosen the nut on the relief valve.

9.Use an Allen wrench to adjust the relief valve. Turn clockwise to raise the pressure and counterclockwise to reduce the pressure. Tighten the nut and retest.

10.Check both the 5 and 8 gallon flow settings and then follow the same procedure to test the other circuit (each circuit has its own relief valve).

16 ► HP TWIN8 User Manual